def convert_hex_to_bin(hex_str):
    return bin(int(hex_str, 16))[2:].zfill(8)


def format_bin(bin_str):
    return bin_str.replace("1", "x").replace("0", " ")


def main():
    hex_list = ["FF 81 BD A5 A5 BD 81 FF",
            "AA 55 AA 55 AA 55 AA 55",
            "3E 7F FC F8 F8 FC 7F 3E",
            "93 93 93 F3 F3 93 93 93"]

    for image in hex_list:
        for line in image.split():
            print(format_bin(convert_hex_to_bin(line)))

if __name__ == "__main__":
    main()